The invention relates to a rotor or guide wheel of a turbine engine which is equipped with a shroud ring.
In turbine wheels of this general type, the boundary layer of the flow which forms along the side of the shroud ring oriented toward the blade channel experiences a pressure in the vicinity of the compression side of the blades which is approximately equal to the total inlet pressure preceding the cascade. The medium flowing into this boundary layer is braked there and is set into motion in the direction toward the intake side by the pressure drop in the blade channel directed from the compression side toward the intake side. The result is a secondary flow in the blade channel, which leads to the known problem of secondary or peripheral losses.
As a result of the same pressure drop which produces the pressure differences in the blade channel, a portion of the medium is also removed by suction via the outer side of the shroud ring through the gaps between the sealing combs of the labyrinth seal and the outer surface of the shroud ring. This second leakage flow leads to the known problem of gap losses.
In both cases, the diverted medium has a disadvantageous effect on the internal efficiency of the turbine engine.